Chain Reaction
Choose a category and write it on the blackboard. Pick something such as "cities," where the possibilities are numerous. Have each student write the alphabet on a sheet of paper. Give the students five minutes to think of as many items in the given category as they can. Once the time is up, begin the game. Have the first student name a city. Tell the next student to name another city that begins with the last letter of the previous answer. Continue around the room, eliminating students when they can no longer respond.
Password
Select two students to be guessers. Have them stand in front of the class while you write a secret word on the chalkboard behind them. Ask the kids to give the guessers one-word clues as to the identity of the secret word. Students must raise their hands and be called directly by one of the guessers to answer. Replace the guesser who reveals the password with the student who volunteers the clue. Be sure to adapt the game to the students' abilities.
Grapevine
Turn the class into a bunch of gossips. Arrange them in a large circle, seated about an arm's length from each other. Whisper a phrase, sentence or tongue-twister into the first student's ear. Do not repeat the message. That student must then whisper the message she heard into the next classmate's ear. The message will travel around the circle and most likely be lost in translation by the end. The results are often hilarious.
Silence
Silence is not only golden; it can also be a lot of fun. Instruct students to organize themselves into groups. The only stipulation is that they must do it in silence. Adapt the groups to whatever the class is studying. For instance, give each student the name of a president written on a piece of paper. Have them wear their presidential name tags and arrange themselves in order of presidencies. The game of silence encourages students to work as a team. Group categories are endless and the silence makes learning more memorable.